我有一个家庭作业，我需要在十进制，二进制和十六进制之间进行三向转换。我需要帮助的函数是将十进制转换为十六进制。我几乎不了解十六进制，但仍然如何将十进制转换为十六进制。我需要一个接收int dec并返回String hex的函数。不幸的是我没有这个功能的任何草稿，我完全迷失了。我只有这个。
public static String decToHex(int dec)
{
String hex = "";
return hex;
}
此外，我不能使用像Integer.toHexString（）或其他任何东西的预制函数，我需要实际制作算法，否则我就不会学到任何东西。
一种可能的方案：
import java.lang.StringBuilder;
class Test {
private static final int sizeOfIntInHalfBytes = 8;
private static final int numberOfBitsInAHalfByte = 4;
private static final int halfByte = 0x0F;
private static final char[] hexDigits = {
'0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
};
public static String decToHex(int dec) {
StringBuilder hexBuilder = new StringBuilder(sizeOfIntInHalfBytes);
hexBuilder.setLength(sizeOfIntInHalfBytes);
for (int i = sizeOfIntInHalfBytes - 1; i >= 0; --i)
{
int j = dec & halfByte;
hexBuilder.setCharAt(i, hexDigits[j]);
dec >>= numberOfBitsInAHalfByte;
}
return hexBuilder.toString();
}
public static void main(String[] args) {
int dec = 305445566;
String hex = decToHex(dec);
System.out.println(hex);
}
}
输出：
1234BABE
无论如何，有一个库方法：
String hex = Integer.toHexString(dec);
查看下面的代码，了解十进制到十六进制的转换，
import java.util.Scanner;
public class DecimalToHexadecimal
{
public static void main(String[] args)
{
int temp, decimalNumber;
String hexaDecimal = "";
char hexa[] = {'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
Scanner sc = new Scanner(System.in);
System.out.print("Please enter decimal number : ");
decimalNumber = sc.nextInt();
while(decimalNumber > 0)
{
temp = decimalNumber % 16;
hexaDecimal = hexa[temp] + hexaDecimal;
decimalNumber = decimalNumber / 16;
}
System.out.print("The hexadecimal value of " + decimalNumber + " is : " + hexaDecimal);
sc.close();
}
}
您可以在以下链接>> java convert decimal to hexadecimal中了解有关将十进制转换为十六进制的不同方法的更多信息。
以下将十进制转换为带有时间复杂度的Hexa Decimal：O（n）线性时间，没有任何java内置函数
private static String decimalToHexaDecimal(int N) {
char hexaDecimals[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
StringBuilder builder = new StringBuilder();
int base= 16;
while (N != 0) {
int reminder = N % base;
builder.append(hexaDecimals[reminder]);
N = N / base;
}
return builder.reverse().toString();
}
最简单的方法是：
String hexadecimalString = String.format("%x", integerValue);
转换DECIMAL -to-> BINARY，OCTAL，HEXADECIMAL的代码
public class ConvertBase10ToBaseX {
enum Base {
/**
* Integer is represented in 32 bit in 32/64 bit machine.
* There we can split this integer no of bits into multiples of 1,2,4,8,16 bits
*/
BASE2(1,1,32), BASE4(3,2,16), BASE8(7,3,11)/* OCTAL*/, /*BASE10(3,2),*/
BASE16(15, 4, 8){
public String getFormattedValue(int val){
switch(val) {
case 10:
return "A";
case 11:
return "B";
case 12:
return "C";
case 13:
return "D";
case 14:
return "E";
case 15:
return "F";
default:
return "" + val;
}
}
}, /*BASE32(31,5,1),*/ BASE256(255, 8, 4), /*BASE512(511,9),*/ Base65536(65535, 16, 2);
private int LEVEL_0_MASK;
private int LEVEL_1_ROTATION;
private int MAX_ROTATION;
Base(int levelZeroMask, int levelOneRotation, int maxPossibleRotation) {
this.LEVEL_0_MASK = levelZeroMask;
this.LEVEL_1_ROTATION = levelOneRotation;
this.MAX_ROTATION = maxPossibleRotation;
}
int getLevelZeroMask(){
return LEVEL_0_MASK;
}
int getLevelOneRotation(){
return LEVEL_1_ROTATION;
}
int getMaxRotation(){
return MAX_ROTATION;
}
String getFormattedValue(int val){
return "" + val;
}
}
public void getBaseXValueOn(Base base, int on) {
forwardPrint(base, on);
}
private void forwardPrint(Base base, int on) {
int rotation = base.getLevelOneRotation();
int mask = base.getLevelZeroMask();
int maxRotation = base.getMaxRotation();
boolean valueFound = false;
for(int level = maxRotation; level >= 2; level--) {
int rotation1 = (level-1) * rotation;
int mask1 = mask << rotation1 ;
if((on & mask1) > 0 ) {
valueFound = true;
}
if(valueFound)
System.out.print(base.getFormattedValue((on & mask1) >>> rotation1));
}
System.out.println(base.getFormattedValue((on & mask)));
}
public int getBaseXValueOnAtLevel(Base base, int on, int level) {
if(level > base.getMaxRotation() || level < 1) {
return 0; //INVALID Input
}
int rotation = base.getLevelOneRotation();
int mask = base.getLevelZeroMask();
if(level > 1) {
rotation = (level-1) * rotation;
mask = mask << rotation;
} else {
rotation = 0;
}
return (on & mask) >>> rotation;
}
public static void main(String[] args) {
ConvertBase10ToBaseX obj = new ConvertBase10ToBaseX();
obj.getBaseXValueOn(Base.BASE16,12456);
// obj.getBaseXValueOn(Base.BASE16,300);
// obj.getBaseXValueOn(Base.BASE16,7);
// obj.getBaseXValueOn(Base.BASE16,7);
obj.getBaseXValueOn(Base.BASE2,12456);
obj.getBaseXValueOn(Base.BASE8,12456);
obj.getBaseXValueOn(Base.BASE2,8);
obj.getBaseXValueOn(Base.BASE2,9);
obj.getBaseXValueOn(Base.BASE2,10);
obj.getBaseXValueOn(Base.BASE2,11);
obj.getBaseXValueOn(Base.BASE2,12);
obj.getBaseXValueOn(Base.BASE2,13);
obj.getBaseXValueOn(Base.BASE2,14);
obj.getBaseXValueOn(Base.BASE2,15);
obj.getBaseXValueOn(Base.BASE2,16);
obj.getBaseXValueOn(Base.BASE2,17);
System.out.println(obj.getBaseXValueOnAtLevel(Base.BASE2, 4, 1));
System.out.println(obj.getBaseXValueOnAtLevel(Base.BASE2, 4, 2));
System.out.println(obj.getBaseXValueOnAtLevel(Base.BASE2, 4, 3));
System.out.println(obj.getBaseXValueOnAtLevel(Base.BASE2, 4, 4));
System.out.println(obj.getBaseXValueOnAtLevel(Base.BASE16,15, 1));
System.out.println(obj.getBaseXValueOnAtLevel(Base.BASE16,30, 2));
System.out.println(obj.getBaseXValueOnAtLevel(Base.BASE16,7, 1));
System.out.println(obj.getBaseXValueOnAtLevel(Base.BASE16,7, 2));
System.out.println(obj.getBaseXValueOnAtLevel(Base.BASE256, 511, 1));
System.out.println(obj.getBaseXValueOnAtLevel(Base.BASE256, 511, 2));
System.out.println(obj.getBaseXValueOnAtLevel(Base.BASE256, 512, 1));
System.out.println(obj.getBaseXValueOnAtLevel(Base.BASE256, 512, 2));
System.out.println(obj.getBaseXValueOnAtLevel(Base.BASE256, 513, 2));
}
}
简单：
public static String decToHex(int dec)
{
return Integer.toHexString(dec);
}
我需要一个接受int dec并返回String hex的函数。
我从http://introcs.cs.princeton.edu/java/31datatype/Hex2Decimal.java.html找到了更优雅的解决方案。我从原来改变了一点（见编辑）
// precondition: d is a nonnegative integer
public static String decimal2hex(int d) {
String digits = "0123456789ABCDEF";
if (d <= 0) return "0";
int base = 16; // flexible to change in any base under 16
String hex = "";
while (d > 0) {
int digit = d % base; // rightmost digit
hex = digits.charAt(digit) + hex; // string concatenation
d = d / base;
}
return hex;
}
免责声明：我在编码面试中使用此算法。我希望这个解决方案不会太受欢迎:)
编辑2016年6月17日：我添加了base变量，以便灵活地更改为任何基数：二进制，八进制，7的基数...
根据评论，这个解决方案是最优雅的，所以我删除了Integer.toHexString()的实现。
编辑2015年9月4日：我找到了一个更优雅的解决方案http://introcs.cs.princeton.edu/java/31datatype/Hex2Decimal.java.html
考虑下面的dec2m方法，从dec到hex，oct或bin的转换。
样本输出是
28 dec == 11100 bin
28 dec == 34 oct
28 dec == 1C hex
public class Conversion {
public static void main(String[] argv) {
int x = 28; // sample number
if (argv.length > 0)
x = Integer.parseInt(argv[0]); // number from command line
System.out.printf("%d dec == %s bin\n", i, dec2m(x, 2));
System.out.printf("%d dec == %s oct\n", i, dec2m(x, 8));
System.out.printf("%d dec == %s hex\n", i, dec2m(x, 16));
}
static String dec2m(int N, int m) {
String s = "";
for (int n = N; n > 0; n /= m) {
int r = n % m;
s = r < 10 ? r + s : (char) ('A' - 10 + r) + s;
}
return s;
}
}
另一种可能的方案
public String DecToHex(int dec){
char[] hexDigits = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'A', 'B', 'C', 'D', 'E', 'F'};
String hex = "";
while (dec != 0) {
int rem = dec % 16;
hex = hexDigits[rem] + hex;
dec = dec / 16;
}
return hex;
}
这是任何数字的代码：
import java.math.BigInteger;
public class Testing {
/**
* @param args
*/
static String arr[] ={"0","1","2","3","4","5","6","7","8","9","A","B","C","D","E","F"};
public static void main(String[] args) {
String value = "214";
System.out.println(value + " : " + getHex(value));
}
public static String getHex(String value) {
String output= "";
try {
Integer.parseInt(value);
Integer number = new Integer(value);
while(number >= 16){
output = arr[number%16] + output;
number = number/16;
}
output = arr[number]+output;
} catch (Exception e) {
BigInteger number = null;
try{
number = new BigInteger(value);
}catch (Exception e1) {
return "Not a valid numebr";
}
BigInteger hex = new BigInteger("16");
BigInteger[] val = {};
while(number.compareTo(hex) == 1 || number.compareTo(hex) == 0){
val = number.divideAndRemainder(hex);
output = arr[val[1].intValue()] + output;
number = val[0];
}
output = arr[number.intValue()] + output;
}
return output;
}
}
我会用的
Long a = Long.parseLong(cadenaFinal, 16 );
因为有一些十六进制可能大于整数，它会抛出异常
这是我的
public static String dec2Hex(int num)
{
String hex = "";
while (num != 0)
{
if (num % 16 < 10)
hex = Integer.toString(num % 16) + hex;
else
hex = (char)((num % 16)+55) + hex;
num = num / 16;
}
return hex;
}
将Decimal转换为HexaDecimal的更好解决方案，这一点不太复杂
import java.util.Scanner;
public class DecimalToHexa
{
public static void main(String ar[])
{
Scanner sc=new Scanner(System.in);
System.out.println("Enter a Decimal number: ");
int n=sc.nextInt();
if(n<0)
{
System.out.println("Enter a positive integer");
return;
}
int i=0,d=0;
String hx="",h="";
while(n>0)
{
d=n%16;`enter code here`
n/=16;
if(d==10)h="A";
else if(d==11)h="B";
else if(d==12)h="C";
else if(d==13)h="D";
else if(d==14)h="E";
else if(d==15)h="F";
else h=""+d;
hx=""+h+hx;
}
System.out.println("Equivalent HEXA: "+hx);
}
}